Terry Newton, one of the best British rugby league players of the last two decades, who earlier this year became the first professional sportsman in the world to test positive for human growth hormone (HGH), was found hanged today.

Newton had left a message on his Facebook page in the early hours of the morning stating "Luv U all but it's end time".

Police were called to his house in Orrell, on the outskirts of Wigan, shortly after 2pm, and discovered the body of the 31-year-old in the garage where, in the past, he had injected himself with the drug, and where he had hidden the 20 syringes from his wife and two young children.

His younger sister, Leanne, died of pneumonia last year after becoming addicted to heroin, and he had regularly taken anti-depressants.

The news filtered to several former club or international team-mates who were at Warrington's Halliwell Jones stadium for the Co-operative Championship grand finals day, and shortly after 5pm the Rugby Football League issued a statement expressing sadness and shock, and sending condolences to Newton's family.

He was seven months into a two-year suspension imposed in February after he had been tested by anti-doping officers last November, shortly after joining Wakefield Trinity from Bradford Bulls.

In several interviews and an autobiography published in May, he spoke of his eagerness to work with the Rugby Football League (RFL) in warning other players of the dangers of drugs, and expressed the hope that he might be able to have the suspension reduced if he provided further information to UK Sport.

He also began running a pub in Wigan, the Ben Jonson, and only last Monday hosted the Salford players for their end-of-season celebrations. But several of those closest to him had been concerned how he would cope with the shame of the ban, and without the day-to-day involvement in rugby league that he had relished since signing for Warrington as a teenager.

His death came the day after his former Wigan team mates saw off the challenge of Leeds to qualify for the English game's showpiece occasion, next weekend's grand final against St Helens.

"Initially it didn't bother me that I wasn't playing rugby, but now watching games it is starting to sink in," he told the BBC in June. Brian Carney, the former Wigan and Great Britain wing who wrote the foreword to Newton's book, said on Sky today: "It's probably been a culmination of things … the comfort blanket of rugby league was taken away and he found himself unable to cope."

Newton was a controversial player. Even before making a senior appearance, the hooker enraged Warrington by accepting a rival offer from Leeds, and he was suspended for a record six months in 2005 following fouls during a derby between Wigan and St Helens.

However he was also highly valued by coaches and team mates. He won the Challenge Cup with Leeds in 1999 and Wigan three years later, and earned 15 Great Britain caps. "He had the heart of a lion," said Barrie McDermott, who packed down with the young Newton at Leeds. "I would have him at the side of me in any battle I went into."

Newton deeply regretted having to leave Wigan for Bradford during that suspension. In his last year with the Bulls, he suffered a series of injuries, which tempted him to research HGH on the internet. In the autumn of 2009, he met another player at an M62 service station, and paid him £150 for a month's supply.

"The HGH came with storage advice on the label – 'keep refrigerated'," he recounted in his book, Coming Clean. "I opened the fridge, looked in and thought 'Not a chance'. Where will she [his wife, Stacey] never find it? Where's quite cold? The garage! She'd never stumble across it in there, and surely that must be cool enough to keep it okay. I pulled my toolbox from the shelf, and slotted it [the case containing the syringes] behind. It fit [sic], perfectly."

He then described his first injection, and added: "I carried on sneaking into my garage in the late afternoon, five days on, two days off, to inject myself."

McDermott said: "It's a huge lesson to any young lad out there who wants take a short cut and find a way to get the edge. It isn't worth it, it's only a game."

Newton played in four Super League Grand Finals at Old Trafford – for Leeds in 1998, and for Wigan three times in four years between 2000-03 – and lost the lot, and the image of him crying on the pitch after the last of those defeats is enduring. On Saturday night, Wigan won at Leeds to reach Old Trafford for the first time since then, but it is not known whether Newton was aware of their victory.

"Everyone at the club is devastated by the news," said Wigan's chairman, Ian Lenagan. "Terry will be remembered as a great player of this club and rugby league in general and a larger than life character."

This week is supposed to be the climax of the rugby league season, beginning at the Man of Steel awards ceremony in Manchester tomorrow when Adrian Morley is favourite to win the British game's most coveted individual award. However no one will feel much like celebrating.

Detecting HGH

There have been rumours about the use of HGH in rugby league and other power-based sports for more than a decade, after it was named as a banned substance by the International Olympic Commission in 1989. It is a naturally occurring anabolic hormone that stimulates the growth of muscle, cartilage and bone, and is therefore used either to increase strength, or to aid training and recovery. But as Newton explains in his book, it had always been thought to be undetectable.

The Rugby Football League have been praised by UK Sport for their pro-active approach to drug testing, and were one of the first sports to introduce blood testing when it became available. Newton's positive test therefore made a worldwide impact, prompting the IOC to identify it as a warning to all athletes, and a Canadian footballer has reportedly become the second player to be caught after a number of North American leagues introduced blood testing